1. Field
Example embodiments relate to semiconductor devices, and more particularly, to a high electron mobility transistor (HEMT) including a semiconductor doped layer formed in a recessed region of first and second semiconductor layers.
2. Description of the Related Art
With the advancement of communication technology, research is actively being carried out regarding electronic devices that operate at high frequencies. In particular, much attention is being directed towards field-effect semiconductor devices, such as high electron mobility transistors (HEMTs), as power electronic devices used in a high frequency region.
A HEMT includes a heterojunction structure created by joining together adjacent semiconductor material layers having different band gaps. A semiconductor material layer having a large band gap functions as a donor. By forming a heterojunction with different band gap materials, a 2-dimensional electron gas (2DEG) layer is induced in a semiconductor material layer having a small band gap to improve the movement speed of electrons.
HEMTs may be used to increase the mobility of electron carriers and also be used as a high breakdown voltage transistor that is an example of power electronic devices. A HEMT includes a wide band gap semiconductor, such as a compound semiconductor, and may be used for high voltage applications due to its high breakdown voltage.
In general, since silicon commonly used in semiconductor devices has a low electron mobility, a high source resistance may occur. Thus, research is currently being conducted regarding the use of a Group III-V semiconductor compound in a HEMT. In particular, a gallium nitride (GaN)-based compound is receiving considerable attention as a promising material for HEMTs due to its wide band gap, high electron saturation velocity, and high chemical stability. Thus, HEMTs using GaN-based compounds are being actively developed as high temperature, high output, and high frequency electronic devices.